Memorial Hermann Health System

Operated by MEMORIAL HERMANN HOSPITAL SYSTEM (per NTSB report)

The pilot’s inadequate preflight inspection, which failed to detect the unsecured cowling latches and resulted in the in-flight opening of an engine cowling.

Part: GEARBOX — NO DISCREPANCY (TAIL ROTOR) · airframe 10,002 hrs · 44,902 cycles

SHORTLY AFTER TAKE-OFF, THE T/R CHIP CAUTION LIGHT ILLUMINATED IN FLIGHT. PILOT PERFORMED ONE FUZZ BURNER ACTIVATION, BUT THE LIGHT CAME BACK ON. THE PILOT RETURNED TO BASE AND LANDED UNEVENTFULLY. MECHANIC CHECKED T/R AND INTERMEDIATE GEARBOXES FOR DEBRIS AND FOUND ONLY NORMAL FUZZ. HE CHANGED THE OIL ON BOTH GEARBOXES AND PERFORMED A 10-MINUTE GROUND RUN. CHECKED BOTH CHIP PLUGS AFTER THE GROUND RUN AND FOUND NO DEBRIS. AIRCRAFT WAS RETURNED TO SERVICE WITH NO FURTHER ISSUES.

Part: GEARBOX — NO DISCREPANCY (TAIL ROTOR) · airframe 10,002 hrs · 44,902 cycles

SHORTLY AFTER TAKE-OFF, THE T/R CHIP CAUTION LIGHT ILLUMINATED IN CRUISE FLIGHT. THE PILOT PERFORMED ONE FUZZ BURNER ACTIVATION, BUT THE LIGHT CAME BACK ON. HE RETURNED TO BASE AND LANDED UNEVENTFULLY. MECHANIC CHECKED INT AND T/R GEARBOX CHIP PLUGS AND FOUND ONLY NORMAL FUZZ. HE CHANGED THE OIL IN BOTH GEARBOXES AND PERFORMED A 10-MINUTE GROUND RUN AT FLIGHT IDLE. BOTH PLUGS WERE CHECKED AND FOUND CLEAN. AIRCRAFT WAS RETURNED TO SERVICE WITH NO FURTHER ISSUES.

Part: FUEL CONTROL — INOPERATIVE (NR 1 ENGINE) · airframe 10,545 hrs · 46,527 cycles

WHEN CLIMBING OUT FROM A HELIPAD TO A HIGH HOVER AT HIGH POWER SETTINGS, THE #1 ENGINE DROPPED OFFLINE CAUSING A LARGE TORQUE SPLIT WITH THE #2 ENGINE GOING UP TO MAX OEI TORQUE FOR ABOUT 10 SECONDS WHILE THE PILOT LANDED. THE #1 ENGINE DID NOT RESPOND TO TRIM INPUTS ATTEMPTING TO MATCH THE TORQUES DURING THIS EVENT. THE AIRCRAFT WAS LANDED WITHOUT INCIDENT AND MAINTENANCE WAS CALLED. THE MECHANIC FOUND A DISPLACED PIN AND ROLLER IN THE P2 CHAMBER OF THE #1 FUEL CONTROL. THE FUEL CONTROL WAS CHANGED AND THE AIRCRAFT RETURNED TO SERVICE AFTER VARTOMS ADJUSTMENTS TO THE NEW FUEL CONTROL.

Part: MOTOR — OVERHEATED (ZONE 100) · airframe 10,635 hrs · 47,857 cycles

ABOUT FIVE MINUTES INTO A FLIGHT, IN CRUISE FLIGHT, THE PILOT AND CREW NOTED SMOKE AND A STRONG ELECTRICAL SMELL IN THE CABIN AND COCKPIT OF THE HELICOPTER. THEY OPENED WINDOWS TO VENT THE SMOKE, RETURNED TO BASE AND LANDED UNEVENTFULLY. MAINTENANCE DISCOVERED THE AFT CABIN AIR CONDITIONER BLOWER MOTOR HAD OVERHEATED. THE MOTOR WAS REPLACED AND THE HELICOPTER RETURNED TO SERVICE.

Part: OIL COOLER — SHEARED (M/R GEARBOX) · airframe 9,444 hrs · 42,056 cycles

#2 ENG OIL COOLER, SUSPECTED SHAFT BROKEN. REPORTED #2 ENG OIL TEMP FLUCTUATION. INSP REVEALED #2 ENG OIL COOLER SHAFT SHEARED. REM'D #2 OIL COOLER FAN ASSY. INSTALLED SERVICEABLE FAN ASSY, P/N SAME. PERFORMED GROUND RUN/LEAK CHK W/NO ANOMALIES. ACFT RETURNED TO SERVICE.

Part: PRESSURE SWITCH — FAILED (NR 2 ENGINE)

ON ENG STARTUP, #2 ENG, LOW FUEL PRESS LIGHT ILLUMINATED. REM'D #2 ENG LOW FUEL PRESS SWITCH. INSTALLED NEW PRESSURE SWITCH. PERFORMED GROUND RUN. FUNCTION CHK'D GOOD.

Part: BLOWER MOTOR — INOPERATIVE (AFT CABIN CEILIN) · airframe 8,970 hrs · 40,731 cycles

SHORTLY AFTER TAKEOFF THE MEDICAL CREW OF THIS AIR AMBULANCE HELICOPTER REPORTED A STRONG ELECTRICAL SMELL FROM THE REAR OF THE CABIN. THE PILOT RETURNED TO BASE AND LANDED WITHOUT INCIDENT. MAINTENANCE FOUND THE AFT AIR CONDITIONER BLOWER MOTOR WAS INOPERATIVE AND HAD A STRONG ELECTRICAL SMELL. THE MOTOR WAS REPLACED AND THE AIRCRAFT RETURNED TO SERVICE

Part: CIRCUIT BOARD — FAULTY (ENGINE) · airframe 9,679 hrs · 44,007 cycles

"ENG PA DISC" CAUTION LIGHTS ILLUMINATED ON THE CAD FOR BOTH ENGINES WITH THE TOT INDICATIONS TURNED AMBER. THE PILOT CONTINUED HIS APPROACH AND LANDED WITHOUT INCIDENT. THE MECHANIC FOUND A BAD TOT CIRCUIT BOARD ON THE #2 ENGINE CAUSING A LOW INDICATION FOR THAT ENGINE. THE BOARD WAS REPLACED WITH A SERVICEABLE PART AND THE HELICOPTER RETURNED TO SERVICE.

Part: SPHERICAL BEARIN — WORN (TAIL ROTOR) · airframe 9,825 hrs · 43,362 cycles

ON DEPARTURE AND CLIMB OUT, THE PILOT NOTICED A VIBRATION IN THE T/R PEDALS THAT WOULD INCREASE WITH POWER WAS INCREASES. HE RETURNED TO THE AIRPORT AND LANDED UNEVENTFULLY. MAINTENANCE FOUND THE T/R TEETERING BEARINGS WERE WORN EXCESSIVELY.

Part: PRESSURE SENSOR — LEAKING (ZONE 200) · airframe 9,784 hrs · 43,000 cycles

AFTER THE HELICOPTER WAS STARTED, BUT BEFORE LIFTING INTO A HOVER, THE CREW REPORTED A FUEL SMELL IN THE CABIN. SHUT DOWN ENGINES AND CALLED MAINTENANCE. WITH PRIME PUMP "ON", MECHANIC FOUND THE #2 ENGINE LOW FUEL PRESSURE SENSOR LEAKING FROM THE SPLIT LINE.

Part: DRAIN VALVE — LEAKING (ZONE 200) · airframe 9,043 hrs · 40,434 cycles

MEDICAL CREW REPORTED A FUEL SMELL IN THE CABIN AND PILOT LANDED AT THE NEAREST AIRPORT. MECHANIC FOUND THE #2 ENGINE START DRAIN VALVE LEAKING WHEN THE PRIME PUMP WAS ACTIVATED. FUEL DRAINED FROM THE ENGINE DECK DRAIN TUBE AND BLEW AROUND THE LOWER CLAMSHELL DOOR SEALS AT THE BACK OF THE CABIN ALLOWING FUMES INTO THE CABIN. START DRAIN VALVE WAS REPLACED AND THE AIRCRAFT WAS RETURNED TO SERVICE.

Part: SPAR — CRACKED (ZONE 300) · airframe 8,464 hrs · 38,351 cycles

DURING ROUTINE SCHEDULED INSPECTION FOUND CRACK IN TOP L/H SIDE OF THE VERTICAL FIN MAIN SPAR.

Part: COWLING — TORN (T/R BLADE) · airframe 8,441 hrs

AFTER LANDING, INITIAL VISUAL INSP REVEALED VERTICAL FIN COWLING DAMAGE, VIA TAIL ROTOR STRIKE. SUSPECT VERTICAL FIN COWLING ONLY PARTIALLY SECURED PRIOR TO FLIGHT. DURING FWD FLIGHT, COWLING SEPARATED(NOT A COMPLETE IN-FLIGHT SEPARATION) FROM L/H SIDE, ALLOWING TAIL ROTOR BLADES TO CONTACT COWLING, REPEATEDLY. POST LANDING INSP, REVEALED MINOR DAMAGE TO T/R BLADES, AND SIGNIFICANT DAMAGE TO VERT FIN COWLING(NO MISSING MATERIAL OR PARTS - COWL REMAINED IN TACT AND PARTIALLY ATTACHED TO ACFT, BUT DAMAGED). REPLACED BOTH T/R BLADES W/NEW SERVICEABLE BLADES AND BALANCED TO MFG SPECS. REPLACED VERT FIN COWLING W/SERVICEABLE COWLING. PERFORMED OPERATIONAL CHK FLIGHT W/NO OTHER DEFECTS NOTED OR ANOMALIES. ACFT FULLY RELEASED FOR LINE SERVICE.

Part: TRANSMITTER — FALSE INDICATION (#2 ENGINE TORQUE) · airframe 8,958 hrs · 40,415 cycles

"ENGINE PARAMETERS DISAGREE" CAUTION ILLUMINATED IN FLIGHT SHORTLY AFTER DEPARTURE. PILOT RETURNED TO BASE AND LANDED UNEVENTFULLY. PILOT NOTED THE THE #2 ENGINE TORQUE INDICATION WAS ERRATIC. MAINTENANCE CHANGED THE TORQUE TRANSMITTER

Part: FRAME ANGLE — CRACKED (BS 4015) · airframe 7,801 hrs · 35,104 cycles

ON SCHEDULED AIRFRAME INSPECTION, FOUND CRACKS IN FWD RH BOX BEAM STA4015 WEB (P/N: B533K5141-203), STA4135 WEB (P/N: 533K5141-201), STA4015 CAP EXTRUSION (P/N: B533K5140-203), STA 4135 EXTRUSION CAP (P/N: B533K5140-203) AND THE INNER SKIN PANEL (P/N: B533K5605-211).

Part: PRESSURE SWITCH — FAILED (NR 2 ENG FUEL) · airframe 9,180 hrs

#2 ENG FUEL PRESSURE CAUTION ILLUMINATED DURING START SEQUENCE AND WOULD NOT EXTINGUISH. REM'D AND REPLACED #2 ENG FUEL PRESSURE SWITCH. ENG RUN/LEAK CHK GOOD.

Part: DRAIN VALVE — VAPOR (ZONE 400) · airframe 8,568 hrs

DURING CRUISE FLIGHT, MEDCREW REPORTED FUEL SMELL, ENTERING CABIN AREA. SUSPECT FUEL LEAKAGE VENTING, AND RESIDUAL SMELL INADVERTENTLY VENTING INTO CABIN AREA. REM'D #2 START DRAIN VALVE ASSY. INSTALLED SERVICEABLE START DRAIN VALVE ASSY. NO OTHER DEFECTS NOTED.

Part: PRESSURE SWITCH — FAILED (FUEL SYSTEM) · airframe 9,120 hrs

ON CLIMBOUT, #1 FUEL PRESS ILLUMINATED. ALL ENG PARAMATERS NORMAL. CAUTION EXTINGUISHED AFTER APPROX 5MIN. REPLACED #1 ENG FUEL PRESS SWITCH. INSP FUEL FILTER AS A PRECAUTION. PERFORMED GROUND RUN/LEAK CHK, 2 STARTS EA, W/NO ANOMOLIES. LEAK CHK'D GOOD.

Part: BOX BEAM — CRACKED (BS 4135) · airframe 8,996 hrs · 40,995 cycles

DURING SCHEDULED MAINTENANCE FOUND DAMAGE TO THE FWD RH BOX BEAM STA4135 WEB (P/N: B533K5141-201), STA4135 EXTRUSION CAP (P/N: B533K5140 -203) AND THE INNER SKIN PANEL (P/N: B533K5605-211) IN THE FORM OF CRACKS.

Part: MOTOR — ODOR (AFT CABIN) · airframe 7,998 hrs

CREW REPORTED A RATTLING NOISE AND BURNING SMELL FROM THE REAR CABIN AIR CONDITIONER VENTS. LANDED WITHOUT INCIDENT AND CALLED MAINTENANCE. THE MECHANIC FOUND ONE OF THE DUAL SQUIRREL CAGE IMPELLORS HAD SHIFTED TO ONE SIDE AND WAS RUBBING ON THE FIBERGLASS BLOWER HOUSING. THE AFT BLOWER ASSEMBLY WAS CHANGED AND THE AIRCRAFT WAS RETURNED TO SERVICE.

Part: LATCH HANDLE — SEPARATED (ZONE 600) · airframe 8,629 hrs

R/H OUTSIDE SLIDING DOOR HANDLE SEPARATED FROM AIRCRAFT IN CRUISE FLIGHT. AIRCRAFT CONTINUED FLIGHT SAFELY WITH NO INTERRUPTION. REPLACED DOOR HANDLE. FUNCTION CHK'D GOOD.

Part: TEE FITTING — BLOCKED (ZONE 400)

#2 ENG OIL PRESS ILLUMINATED DURING FLIGHT. DIVERT TO LOCAL AIRPORT(KSGR), FOR PRECAUTIONARY LANDING. UNEVENTFUL AND SAFE LANDING. UPON FURTHER INSP, FOUND "T" FITTING ON ENG, CLOGGED. REPLACED "T" FITTING, AND START DRAIN VALVE, AS REQUIRED. PERFORMED SEVERAL ENG RUNS WITH PWR CHKS. ENGINE PERFORMED TO SPECS, WITHOUT FURTHER ANOMALIES OR DISCREPANCIES. PERFORMED OPERATION CHK FLIGHT. CHK'D GOOD. ACFT RETURNED TO SERVICE. REM'D PARTS, BEING SENT TO MFG, FOR FURTHER INVESTIGATION.

Part: VENT LINE — CLOGGED (ZONE 400)

#2 ENG OIL PRESSURE FLUCTUATED IN FLIGHT INTO CAUTION RANGE, AND INTO NORMAL RANGE. AFTER TROUBLESHOOTING, FOUND OIL TANK EMPTY. FOUND CLOGGED VENT LINE, WHICH ALLOWED OIL TO BE SIPHONED OUT DURING OPERATION. CLEANED P2 AIR LINE AND T FITTING. CLEANED BLEED VALVE FILTER. CLEANED AND INSPECTED ALL CHIP DETECTORS. FILLED OIL TANK TO PROPER LEVEL. PERFORMED OPS CHK FLIGHT AND FOUND SATISFACTORY.

Part: DRIVE BELT — BROKEN (A/C PACK) · airframe 7,286 hrs

DURING FLIGHT, AIRCOND BELT BROKE. REM'D & REPLACED AIRCOND BELT. GROUND RUN CHK GOOD.

Part: PRESSURE SWITCH — FAILED (FUEL SYS) · airframe 7,724 hrs

FUEL PRESSURE CAUTION ON ENGINE #2. THIRD TIME IN THE LAST MONTH. PRESSURE SWITCH REPLACED TWICE. REM'D #2 FUEL PRESS SWITCH. OP'S CHK SATISFACTORY.

Part: PRESSURE SWITCH — FAILED (FUEL SYSTEM) · airframe 7,692 hrs

FUEL PRESSURE CAUTION ON ENG 2, SWITCH ALREADY REPLACED. REM'D #2 FUEL PRESS SWITCH, AND INSTALLED NEW FUEL PRESSURE SWITCH. OP'S CHK SATISFACTORY.

Part: WIRE — BROKEN (NR 1 GENERATOR) · airframe 6,618 hrs

NR 1 GENERATOR DISCONNECT. WAS ABLE TO RESET. INSPECTION REVEALED A BROKEN WIRE AT THE NR 1 GENERATOR. REPAIRED THE WIRE. GROUND RUN. OPS CHECKED GOOD.

Part: PRESSURE SWITCH — FAILED (#1 ENGINE) · airframe 7,408 hrs

NR 1 FUEL PRESSURE LIGHT INTERMITTENTLY ILLUMINATES. REMOVED THE FUEL PRESSURE SWITCH. INSTALLED SERVICEABLE FUEL PRESSURE SWITCH. PERFORMED GROUND RUN, LEAK CHECKED GOOD. ACFT APPROVED FOR RETURN TO SERVICE.

Part: FCU — FAILED (NR 2 ENGINE) · airframe 6,610 hrs

NR 2 ENGINE UNDERSPEED IN-FLIGHT. SUSPECT INTERNAL FAILURE OF FUEL CONTROL. REM'D FUEL CONTROL. INSTALLED SERVICEABLE FUEL CONTROL. PERFORMED GROUND RUN/LK CHK. PERFORMED OPERATIONAL CHK FLIGHT. CHK'D GOOD. NO ANOMALIES. ACFT RETURNED TO SERVICE.

Part: UNKNOWN — ODOR (CABIN) · airframe 6,059 hrs

STRONG RUBBER/ELECTRICAL SMELL COMING FROM REAR CABIN AC VENTS. SMELL DISAPPEARED WITH AC TURNED OFF.

Part: THERMOCOUPLE — FAILED (NR 2 ENGINE) · airframe 6,244 hrs

IN CRUISE FLIGHT, THE ENG PA DIS LIGHTS ILLUMINATED IN BOTH LANES OF THE CAD. PERFORMED ENGRUN, TO REVEAL #2 ENG TEMP DIFFERENCE OF APPROX. 200DEG. REM'D ALL 3 THERMOCOUPLES. INSTALLED 3EA SERVICEABLE THERMOCOUPLES. PERFORMED GROUND RUN, FUNCTION CHK'D GOOD. PERFORMED OPERATIONAL CHK FLIGHT. NO DEFECTS FOUND. ACFT RETURNED TO SERVICE.

Part: VENT LINE — LOOSE (EXPANSION TANK) · airframe 6,901 hrs

FUEL SMELL NOTICEABLE IN CABIN, DURING FLIGHT. INSPECTED, FOUND EXPANSION TANK VENT LINE LEAKING AT FITTING. INSPECTED AND REPAIRED LINE, AS REQUIRED. NO OTHER DEFECTS NOTED. ACFT RETURNED TO SERVICE.

Part: PRESSURE SWITCH — FAILED (LT ENGINE) · airframe 6,193 hrs

NR 1 ENG FUEL PRESSURE LIGHT ILLUMINATED DURING FLIGHT/APPROACH. REPLACED LOW FUEL PRESSURE SWITCH WITH SERVICEABLE PART. PERFORMED GROUND RUN/LK CHK. CHK'D GOOD.

Part: PACKING — FAILED (SHUTOFF VALVE) · airframe 5,466 hrs

AFTER PATIENT LOADING, DURING FINAL WALK AROUND, MED CREW NOTICED FUEL LEAKING FROM #2 ENGINE. MECHANIC, UPON FURTHER INSPECTION, FOUND FUEL SHUTOFF VALVE LEAKING AT FILTER BOWL. REPLACED PACKING. LEAK CHK GOOD. NO OTHER DEFECTS NOTED.

Part: PACKING — FAILED (SHUTOFF VALVE) · airframe 5,466 hrs

ON SCENE, ACFT RUNNING, AFTER PATIENT LOADING, MED CREW PERFORMING FINAL WALK AROUND, NOTICED FUEL LEAKING FROM #2 ENGINE COWLING. ACFT SHUTDOWN. MECHANIC PERFORMED FURTHER INSP, REVEALING FUEL FILTER BOWL SHUT OFF VALVE LEAKING. REM'D & REPLACED PACKING. FUNCTIONAL/LEAK CHECKED GOOD.

Part: FCU — LEAKING (ENGINE)

WITH PRIME PUMP ON, FUEL WAS LEAKING FROM THE OVERBOARD DRAIN IN A STEADY STREAM. WITH ENGINE RUNNING, FUEL WAS LEAKING FROM THE OVERBOARD DRAIN AT A RATE OF 1 DROP EVERY 2 TO 4 SECONDS.

Part: DRAIN VALVE — FAILED (FUEL SYSTEM) · airframe 3,277 hrs · 14,802 cycles

START DRAIN VALVE FAILED INTERNALLY ALLOWING FUEL TO FLOW INTO THE COMPRESSOR THROUGH THE P2 AIR LINE. FUEL BLEW OUT OF THE COMPRESSOR CASE SPLIT LINE AND IGNITED ON TOP OF THE ENGINE CAUSING THE FIRE WARNING LIGHT TO FLICKER ON AND OFF SEVERAL TIMES. PILOT RETURNED TO DEPARTURE PAD AND LANDED SAFELY WITH BOTH ENGINES OPERATING AND PERFORMED AN EMERGENCY SHUTDOWN OF BOTH ENGINES. FIRE WARNING LIGHT HAD GONE OUT AND THE FIRE SELF EXTINGUISHED. THE FIRE BOTTLES WERE NOT DISCHARGED. NO DAMAGE FOUND TO THE COWLING OR IN THE ENGINE COMPARTMENT.

Part: BULB — MALFUNCTIONED (OIL TEMP) · airframe 824 hrs

NR 1 ENG OIL TEMP WENT TO THE RED LINE AND THEN ERRATIC. PILOT SHUTDOWN ENGINE AND MADE A PRECAUTIONARY LANDING. REPLACED TEMP BULB WITH NEW, FUNCTION CHECK GOOD.

Part: CARTRIDGE — UNKNOWN · airframe 746 hrs

CARTRIDGE ORDERED TO REPLACE PUMP THAT THE LIGHT WAS INTERMITTENT. THIS CARTRIDGE WOULD NOT EVEN TURN THE LIGHT OFF AND IT WAS FRESH OUT OF OVERHAUL. PUT ORIGINAL PUMP BACK IN.

Part: ACTUATOR — JAMMED (NR 2 ENGINE) · airframe 428 hrs

IN FLIGHT NR 2 ENGINE TRIM ACTUATOR FULLY RETRACTED, JAMMED, POPPED TRIM CIRCUIT BREAKER. AIRCRAFT LANDED USING MANUAL TRIM. REPLACED ACTUATOR.

Part: LATCH — LOOSE (PAX DOOR) · airframe 213 hrs

DURING CRUISE FLIGHT AT 120 KTS, THE LT SLIDING CABIN DOOR CAME OPEN, SLID ALL THE WAY TO THE STOP AT A HIGH RATE OF SPEED AND POPPED OUT OF THE CENTER GUIDE RAIL. THE MECHANICS FOUND A BOLT VERY LOOSE (3 OR 4 TURNS LOOSE) IN THE LATCHING MECHANISM FRICTION SYS, WHICH ALLOWED THE DOOR HANDLE TO VIBRATE OPEN. THE CENTER GUIDE ARM ABOVE WAS BENT, THE CENTER GUIDE RAIL P/N B520M0037801 WAS BENT OPEN WHERE THE GUIDE POPPED OUT AND THE BACKSTOP P/N B520M4025102 WAS CRACKED. THE DAMAGED PARTS WERE REPLACED, THE LOOSE BOLT WAS REMOVED, CLEANED AND REINSTALLED TO PROPER TORQUE WITH THREAD LOCKING FLUID. NO FURTHER PROBLEMS HAVE OCCURED.

Part: WINDOW — SEPARATED (CREW DOOR) · airframe 10,067 hrs · 4,767 cycles

DURING CLIMB OUT, GOING THROUGH 600 FT, THE SLIDING WINDOW OF THE PILOT'S DOOR WINDOW DEPARTED THE AIRCRAFT. MAINTENANCE FOUND THE TRACK WHERE THE SLIDING WINDOW RIDES WAS DEBONDED FROM THE WINDOW. TRACK WAS REGLUED WITH EPOXY RESIN AND SECURED TO THE WINDOW WITH PANHEAD SCREWS AND NUTS. SOME DEBONDING DETECTED ON WINDOW TRACKS OF OTHER BK117S IN THE FLEET. ALL WINDOW TRACKS ON ALL WINDOWS ON ALL BK117S AND BO105 IN THE FLEET WERE INSPECTED, REBONDED AS NEEDED AND SECURED WITH SCREWS AND NUTS.

Part: TRANSMISSION — FAILED (M/R)

PILOT REPORTED WHINE IN TRANSMISSION FOLLOWED BY LOUD BANG, SEVERE VIBRATIONS, ENGINE NR 1 FIRE WARNING LIGHT, LOSS OF BOTH ENGINES. AUTO-ROTATED SAFELY. AIRCRAFT SEVERELY DAMAGED BY FIRE AFTER LANDING. TEAR-DOWN INSPECTION REVEALED CONTAMINATION BLOCKING OIL PASSAGES TO NR 1 INPUT QUILL OF MAIN TRANSMISSION. INPUT SHAFT HEATED UP AND FAILED CAUSING BENDIX DRIVE SHAFT TO FAIL. THE FAILED DRIVE SHAFT CREATED FOD WHICH WAS INJESTED BY BOTH ENGINES, NO FOD SCREENS. THE DRIVE SHAFT ALSO STRUCK THE TRANSMISSION OIL INLET LINE AND RUPTURED IT. THE OIL WAS IGNITED BY THE HOT QUILL. RECOMMEND REMOVAL OF ALL PLUGS AND MACHINING SCREWS FOR A THOROUGH CLEANING OF TRANSMISSION OIL PASSAGES DURING OVERHAUL.